scholarly journals Interfacial Reactions and Fracture Behavior of Ti Alloy-Ag28Cu Brazing Joints: Influence of Titanium Alloy Composition

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 830 ◽  
Author(s):  
Joachim Gussone ◽  
Galina Kasperovich ◽  
Jan Haubrich ◽  
Guillermo Requena
Keyword(s):  
Titanium Alloys ◽  
Fracture Behavior ◽  
Titanium Substrate ◽  
Tensile Tests ◽  
Coarse Grained ◽  
X Ray ◽  
Fine Grained ◽  
Β Phase ◽  
Brazed Joints ◽  
Crack Paths

Brazing of titanium provides a joining technique suitable for the fabrication of highly-loaded aerospace components, but it still poses numerous challenges, such as the formation of brittle intermetallic interphases. This study of the interphase formation in brazed joints consisting of different titanium alloys (Ti-CP2, Ti-CP4, Ti-6Al-4V, Ti-6Al-2Mo-4Zr-2Sn) and Ag28Cu shows that complex reactions lead to the formation of various intermetallic phases including a Ti2Cu-TiCu boundary zone. The compositions of the titanium alloys influenced the particular microstructures, which have been characterized with various methods including synchrotron X-ray microtomography. Tensile tests evidence high ultimate tensile strengths that are, importantly, not directly limited by the strength of the brazing alloy. The strength of the Ti2Cu-TiCu phase boundary is significantly increased by the alloying elements in Ti-6Al-4V and Ti-6Al-2Mo-4Zr-2Sn and the crack paths change from boundary failure to transcrystalline fracture through TiCu as well as Ag-rich regions. Cu diffusion into the titanium substrate, leading to a coarse grained β-phase that transforms eutectoidally into a lamellar α-Ti + Ti2Cu structure during cooling, occurred in all systems except Ti-6Al-2Mo-4Zr-2Sn where Mo stabilized a fine grained microstructure and enabled the formation of a columnar TiCu structure.

scholarly journals Initial β Grain Size Effect on High-Temperature Flow Behavior of Tb8 Titanium Alloys in Single β Phase Field

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 891
Author(s):  
Qiuyue Yang ◽  
Min Ma ◽  
Yuanbiao Tan ◽  
Song Xiang ◽  
Fei Zhao ◽  
...  
Keyword(s):  
High Temperature ◽  
Titanium Alloys ◽  
Hot Deformation ◽  
Flow Behavior ◽  
Coarse Grained ◽  
Strain Rates ◽  
Processing Parameter ◽  
Fine Grained ◽  
Β Phase ◽  
Different Strains

The high-temperature flow behavior of TB8 titanium alloys with two different grain sizes was investigated in this present work. Results show that a significant characteristic of stress drop is visible at the start stage of the hot deformation process when the strain rates are 100 and 10−1 s−1. With the further increasing of strain, the flow stress initially rises to a maximum value and subsequently attains a plateau for the strain rates of 100 s−1 and a slight decrease for the strain rates of 10−1 s−1. Only dynamic recovery occurs under these deformation conditions. When the strain rates drop to 10−3 s−1, the dynamic recrystallization takes place during hot deformation. The values of deformation activation energy and materials constants at different strains were calculated. The processing maps at different strains were established for the fine- and coarse-grained alloys. The optimal processing parameter for hot processing was attained to be 900 °C/10−3 s−1 for fine-grained alloys and 950 °C/10−3 s−1 for coarse-grained alloys, respectively.

Contact Fracture Behaviors of Ti3SiC2 Synthesized by Hot Pressing Using TiCx and Si Powder Mixture

2005 ◽  
Vol 486-487 ◽  
pp. 217-220
Author(s):  
Sung Sic Hwang ◽  
Sang Whan Park ◽  
Seong Jai Cho ◽  
Dong Bok Lee
Keyword(s):  
Plastic Deformation ◽  
Fracture Behavior ◽  
Hertzian Contact ◽  
Coarse Grained ◽  
Vickers Indentation ◽  
Hertzian Indentation ◽  
Fine Grained ◽  
Fracture Behaviors ◽  
Hertzian Contact Stress ◽  
Contact Fracture

The contact fracture behaviors of fine-grained Ti3SiC2 and coarse-grained high purity Ti3SiC2 are examined by the Hertzian indentation and Vickers indentation technique. The Vickers hardness of bulk Ti3SiC2 is as low as 5.3~6.3 Gpa, and the Hertzian contact stress-strain curves for Ti3SiC2 deviate much from linearity, which resembles the fracture behavior of a ductile metal rather than a brittle ceramic. The contact damages by both Vickers indentation and Hertzian indentation reveal a fairly good plastic deformation nature of Ti3SiC2. Un-reacted TiCx in fine-grained Ti3SiC2 may impede the plastic deformation by slip along basal plan inside Ti3SiC2 grain, making Ti3SiC2 less plastic under loading.

The Impact of Grain Size on Oxidation Behavior of TP304H Austenitic Stainless Steel at High Temperature in Air

2011 ◽  
Vol 117-119 ◽  
pp. 990-994
Author(s):  
Wei Wei ◽  
Zhi Wu Wang ◽  
Mao Lin Liu
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Oxide Scale ◽  
Grain Refinement ◽  
Coarse Grained ◽  
X Ray ◽  
Fine Grained ◽  
Different Grain Size ◽  
The Impact

Exposed to 650°C air, TP304H stainless steel with two different grain size was oxidized at this temperature. At the meantime, comparison of their oxidation was through the oxidation kinetics curves and analysis of the morphology and composition of oxide scale which conducted by SEM and X-ray. The results showed that the oxidation rate of TP304H stainless steel was slowed down by grain refinement and oxide scale of fine-grained TP304H steel was thinner than that of coarse-grained steel. The nucleation and the growth of nuclei of coarse-grained oxide scale were more rapid. In addition, the grain refinement of austenitic stainless steel accelerated the diffusivity of Cr and made for the formation of dense and continuous oxide scale, so that the oxidation of stainless steel can be effectively inhabited.

scholarly journals Ti–Zr–Si–Nb Nanocrystalline Alloys and Metallic Glasses: Assessment on the Structure, Thermal Stability, Corrosion and Mechanical Properties

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1551
Author(s):  
Camelia Gabor ◽  
Daniel Cristea ◽  
Ioana-Laura Velicu ◽  
Tibor Bedo ◽  
Andrea Gatto ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Titanium Alloys ◽  
Young’S Modulus ◽  
Melt Spinning ◽  
Young's Modulus ◽  
Structural Features ◽  
Input Power ◽  
X Ray ◽  
Β Phase

The development of novel Ti-based amorphous or β-phase nanostructured metallic materials could have significant benefits for implant applications, due to improved corrosion and mechanical characteristics (lower Young’s modulus, better wear performance, improved fracture toughness) in comparison to the standardized α+β titanium alloys. Moreover, the devitrification phenomenon, occurring during heating, could contribute to lower input power during additive manufacturing technologies. Ti-based alloy ribbons were obtained by melt-spinning, considering the ultra-fast cooling rates this method can provide. The titanium alloys contain in various proportions Zr, Nb, and Si (Ti60Zr10Si15Nb15, Ti64Zr10Si15Nb11, Ti56Zr10Si15Nb19) in various proportions. These elements were chosen due to their reported biological safety, as in the case of Zr and Nb, and the metallic glass-forming ability and biocompatibility of Si. The morphology and chemical composition were analyzed by scanning electron microscopy and energy-dispersive X-ray spectroscopy, while the structural features (crystallinity, phase attribution after devitrification (after heat treatment)) were assessed by X-ray diffraction. Some of the mechanical properties (hardness, Young’s modulus) were assessed by instrumented indentation. The thermal stability and crystallization temperatures were measured by differential thermal analysis. High-intensity exothermal peaks were observed during heating of melt-spun ribbons. The corrosion behavior was assessed by electrocorrosion tests. The results show the potential of these alloys to be used as materials for biomedical applications.

scholarly journals Effect of microstructure on the formability of Ti21S alloy

2021 ◽  
Author(s):  
Cai Hu ◽  
Lionel Leotoing ◽  
Philippe Castany ◽  
Dominique Guines ◽  
Thierry Gloriant
Keyword(s):  
Titanium Alloys ◽  
Weight Ratio ◽  
Tensile Tests ◽  
Forming Limit ◽  
Uniaxial Tensile ◽  
Β Phase ◽  
Wide Range ◽  
Tension State ◽  
And Performance ◽  
Effect Of Microstructure

Titanium alloys find a wide range of uses, especially in the aeronautic industry because of a combination of favorable specifications in terms of strength-to-weight ratio, corrosion resistance and performance at high temperature. If many works are interested in mechanical properties, as well as microstructure, few of them studied the effect of microstructure on formability. The aim of this work is to study the influence of the microstructure on the formability of β metastable titanium alloys (Ti21S) which are increasingly used in aeronautical applications. For this purpose, two different heat treatments are performed on Ti21S alloy in order to propose different microstructures. Based on uniaxial tensile tests, the elastoplastic hardening behavior and the limit strain in the uniaxial tension state are obtained and allow to determine one point of the forming limit curve (FLC). From these experimental observations, it is shown that the microstructure has an important effect on the formability: precipitation of α phase reduces the formability in comparison with full β phase microstructure. Finally, a finite element M-K model is used and calibrated to predict the whole FLC for the different investigated microstructures.

The Effect of α-Phase Grains Morphology in Initial Microstructure on Superplasticity of Two-Phase Titanium Alloys

2016 ◽  
Vol 838-839 ◽  
pp. 143-149 ◽  
Author(s):  
Maciej Motyka ◽  
Jan Sieniawski
Keyword(s):  
Plastic Deformation ◽  
Titanium Alloys ◽  
Superplastic Deformation ◽  
Thermomechanical Processing ◽  
Ti6al4v Alloy ◽  
Two Phase ◽  
Fine Grained ◽  
Β Phase ◽  
Α Phase ◽  
Heating Up

It is generally accepted that fine-grained and equiaxed microstructure enables superplastic deformation of two-phase titanium alloys. Appropriate microstructure is usually developed in the thermomechanical processing with careful selection of the parameters of plastic deformation and heat treatment. Based on results of own research in this area increased superplasticity was found in Ti6Al4V alloy having microstructure containing highly deformed and elongated α-grains – considerably different from equiaxed ones. It was found that during heating up and first stage of superplastic deformation fragmentation of elongated α-phase grains occurred, followed by formation and growth of globular grains of that phase. Particular role of quenching of the Ti6Al4V alloy from the stable β-phase temperature range in thermomechanical processing was identified. It leads to increase of elongation coefficient of α-phase grains after plastic deformation but also restrains nucleation of the precipitates of secondary α-phase in further stages of thermomechanical processing. It was established that developed phase morphology of the alloy determined its hot plasticity – especially in the range of low strain rates typical for superplastic deformation.

An X-ray method for studying orientation of micaceous minerals in shales, clays, and similar materials

1953 ◽  
Vol 30 (220) ◽  
pp. 71-78 ◽  
Author(s):  
G. W. Brindley
Keyword(s):  
Bedding Plane ◽  
Coarse Grained ◽  
Ray Method ◽  
X Ray ◽  
Fine Grained ◽  
Sedimentary Deposits ◽  
Degree Of Orientation ◽  
Similar Materials ◽  
Ray Methods ◽  
Microscopic Techniques

Micaceous minerals, such as the micas, the chlorites, and most clay minerals, usually develop as thin lamellae parallel to the crystallographic basal plane (001). In sedimentary deposits these lamellae tend to lie parallel to the bedding plane and in slates parallel to the cleavage. Their degree of orientation is likely to vary with the conditions of formation of the material, and in the case of slates Bates (1947) has shown that it is closely related to their fissility. In relatively coarse-grained materials the degree of orientation may be studied directly by suitable microscopic techniques, but with fine-grained materials X-ray methods must be used, and even with coarser-grained materials the use of X-ray methods may have advantages, especially if a scanning technique, such as that described by Thewlis and Pollock (1950), is employed.

scholarly journals Quantitative grain-scale ferroic domain volume fractions and domain switching strains from three-dimensional X-ray diffraction data

2015 ◽  
Vol 48 (3) ◽  
pp. 882-889 ◽  
Author(s):  
Jette Oddershede ◽  
Marta Majkut ◽  
Qinghua Cao ◽  
Søren Schmidt ◽  
Jonathan P. Wright ◽  
...  
Keyword(s):  
Domain Switching ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Bulk Sample ◽  
Coarse Grained ◽  
X Ray Diffraction ◽  
X Ray ◽  
Volume Fractions ◽  
Fine Grained ◽  
Ferroic Materials

A method for the extension of the three-dimensional X-ray diffraction technique to allow the extraction of domain volume fractions in polycrystalline ferroic materials is presented. This method gives access to quantitative domain volume fractions of hundreds of independent embedded grains within a bulk sample. Such information is critical to furthering our understanding of the grain-scale interactions of ferroic domains and their influence on bulk properties. The method also provides a validation tool for mesoscopic ferroic domain modelling efforts. The mathematical formulations presented here are applied to tetragonal coarse-grained Ba0.88Ca0.12Zr0.06Ti0.94O3and rhombohedral fine-grained (0.82)Bi0.5Na0.5TiO3–(0.18)Bi0.5K0.5TiO3electroceramic materials. The fitted volume fraction information is used to calculate grain-scale non-180° ferroelectric domain switching strains. The absolute errors are found to be approximately 0.01 and 0.03% for the tetragonal and rhombohedral cases, which had maximum theoretical domain switching strains of 0.47 and 0.54%, respectively. Limitations and possible extensions of the technique are discussed.

On the completeness of the β→ω transformation in metastable β titanium alloys

2017 ◽  
Vol 50 (1) ◽  
pp. 283-287 ◽  
Author(s):  
Jana Šmilauerová ◽  
Petr Harcuba ◽  
Dominik Kriegner ◽  
Václav Holý
Keyword(s):  
Single Crystal ◽  
Titanium Alloys ◽  
Radial Profile ◽  
Diffraction Maximum ◽  
X Ray Diffraction ◽  
X Ray ◽  
Β Phase ◽  
Ω Phase ◽  
Diffraction Peaks ◽  
Integrated Intensities

The completeness of the β→ω transformation in ω particles in a Ti–8 at.%Mo (Ti–15 wt%Mo) single crystal was investigated by measuring the X-ray diffraction maximum 20{\overline 2}2, which is forbidden in both the pure body-centred cubic β phase and the hexagonal ω phase, and also the diffraction maxima 0001, 0002 and 10{\overline 1}1, which are forbidden in the β phase and allowed in ω. From a comparison of the integrated intensities and widths of the diffraction peaks with simulations, the effective (mean) degree of the transformation was determined and the radial profile of the transformation degree in an ω particle was estimated.

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